The present invention relates to a connector, in particular, to a connector that is attached to an end portion of a coaxial cable.
A connector for connecting a coaxial cable has been conventionally used, and a connector 1 illustrated in FIG. 9 is disclosed by JP H1-124669 U, for example. The connector 1 includes a shell 3 with which a connection nut 2 is rotatably engaged and a fastening ring 4, while a coaxial cable 5 has a structure in which an outer periphery of a central conductor 6 is covered by an insulator 7, and an outer periphery of the insulator 7 is covered by a shield member 8 and a casing 9.
For attachment of the connector 1 to the coaxial cable 5, firstly, the coaxial cable 5 is passed through the fastening ring 4, a given length of the casing 9 at a front end of the coaxial cable 5 is removed, and thereafter the shield member 8 is folded back onto the outer periphery of the coaxial cable 5 such that the insulator 7 is exposed. In this state, a cylindrical portion 3A of the shell 3 of the connector 1 is inserted between the insulator 7 and the shield member 8 of the coaxial cable 5, and the fastening ring 4 is moved toward the connection nut 2 until coming into contact with the shell 3 as illustrated in FIG. 10 and is deformed and tightened by a tool (not shown), whereby attachment of the connector 1 is completed.
In this process, the shield member 8 and the casing 9 of the coaxial cable 5 are sandwiched between the cylindrical portion 3A of the shell 3 and the fastening ring 4 of the connector 1 and compressed in a radial direction of the coaxial cable 5 by the fastening ring 4. The connector 1 is held so as not to fall off from the coaxial cable 5 in this manner.
Meanwhile, since the cylindrical member 3A of the shell 3 of the connector 1 is inserted between the insulator 7 and the shield member 8 of the coaxial cable 5, the shield member 8 and the casing 9 form a slanted surface that becomes thicker toward the connection nut 2 of the connector 1, and from the above-described shield member 8 and the casing 9, an inner surface of the fastening ring 4 receives a normal force having a force component exerted in a direction away from the connection nut 2. Hence, there is a problem that the fastening ring 4 readily falls off during the process for attachment of the connector 1.
In addition, there arises another problem that the connector 1 enlarges when, in order to prevent the fastening ring 4 from falling off, the lengths of the cylindrical portion 3A of the shell 3 and the fastening ring 4 in an axial direction are increased for the larger compressed areas of the shield member 8 and the casing 9 to be pressed in the radial direction of the coaxial cable 5 by the fastening ring 4 and the increased friction force between the fastening ring 4 and the folded-back shield member 8.